Cytotoxic T-cell epitopes

ABSTRACT

The present invention provides cytotoxic Epstein-Barr virus T-cell epitopes. The epitopes are selected from the group consisting of QAKWRLQTL, RYSIFFDY, HLAAQGMAY, YPLHEQHGM, SVRDRLARL, AVLLHEESM, VSFIEFVGW, FRKAQIQGL, PYLFWLAAI, TVFYNIPPMPL, PGDQLPGFSDGRACPV, VEITPYKPTW, and variants thereof. In addition, the present invention provides compositions including these epitopes for use in inducing CTL&#39;s in a subject.

FIELD OF THE INVENTION

The present invention relates to cytotoxic T-cell (CTL) epitopes within Epstein-Barr virus. The present invention also relates to the use of the epitopes in subunit vaccines.

BACKGROUND OF THE INVENTION

Epstein-Barr virus (EBV) is a herpes virus that infects approximately 80% of individuals in Western societies. Following primary infection, a life long latent EBV infection of B cells is established. When primary infection is delayed until adolescence, which occurs in 10-20% of individuals in Western societies, there is an approximately 50% chance of developing infectious mononucleosis.

EBV has the very useful property of being able to "immortalise" or transform human B cells. These transformed B cells (referred to as LCLs) have the potential for essentially unlimited growth in the laboratory. There are two methods by which these LCLs can be established. Firstly, they may be established by the use of a common strain of EBV, referred to as B95.8. The LCL that is established is infected with this strain of virus. Secondly, LCLs may be generated using the latently infected B cells, present in all EBV immune individuals as a source of transforming virus. In this case, the LCL that emerges is transformed with the strain of EBV naturally present in any given EBV immune individual (referred to as spontaneous LCL).

There are two EBV types, A and B. The A type appears to predominate in the majority of lymphoid infections of healthy seropositive individuals. In such individuals, latently infected B cells appear to be controlled by CD8+ cytotoxic T cells (CTL) specific for the latent antigens, which include the EBV nuclear antigens (EBNAs) 2-6 and the latent membrane antigens (LMP) 1-3 (Moss, D. J. et al. 1992). Recent developments suggests that CD4+ CTL may also play a part in controlling this infection. These CTL are known to recognise short peptide epitopes derived from antigenic determinants in association with MHC class I molecules on the surface of an appropriate antigen presenting cell. LCLs displaying HLA class I and II alleles and presenting epitopes within EBV latent antigens are frequently used as a target cell for defining the specificity of CTL clones.

As whole virus or recombinant vaccines based on full length latent proteins are considered potentially oncogenic, an EBV vaccine based on CTL epitopes derived from the latent antigens is currently being developed (Moss, D. J. et al 1993). Khanna et al, (1992) have previously described several CTL epitopes.

SUMMARY OF THE INVENTION

In a first aspect the present invention consists in cytotoxic T-cell epitopes from Epstein-Barr virus.

More specifically, there is provided twelve cytotoxic T-cell epitopes from the Epstein-Barr virus latent antigens having the amino acid sequences QAKWRLQTL SEQ ID NO:11, RYSIFFDY SEQ ID NO:13, HLAAQGMAY SEQ ID NO:5, YPLHEQHGM SEQ ID NO:23 (YPLHKOHGM SEQ ID NO:25, YRLHEOHGM SEQ ID NO:26, YPLHEORGM SEQ ID NO:24) SVRDRLARL SEQ ID NO:15, AVLLHEESM SEQ ID NO:1 (TVLLHEESM SEQ ID NO:19 and TALLHEESM SEQ ID NO:16), VSFIEFVGW SEQ ID NO:22, FRKAQIQGL SEQ ID NO:3, PYLFWLAAI SEQ ID NO:10, TVFYNIPPMPL SEQ ID NO:18, PGDQLPGFSDGRACPV SEQ ID NO:9 and VEITPYKPTW SEQ ID NO:20. In addition, the underlined amino acid sequences in brackets are variants of the aforementioned sequence and have been sequenced from geographically different isolates of Epstein-Barr virus. It has not as yet been established whether these variants are CTL epitopes.

In a second aspect the present invention consists in a composition for use in inducing CTL's in a subject, the composition comprising at least one cytotoxic Epstein-Barr virus T-cell epitope according to the first aspect of the present invention in admixture with at least one pharmaceutical acceptable adjuvant, carrier, diluent or excipient.

In a third aspect the present invention consists in a method of preparing a composition for use in inducing CTL's in a subject, the method comprising admixing at least one cytotoxic Epstein-Barr virus T-cell according to the first aspect of the present invention with at least one pharmaceutical acceptable adjuvant, carrier, diluent or excipient.

As used herein the term "subject" is intended to cover human and non-human animals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Screening overlapping peptides of EBNA4 on PHA blast cells for reactivity.

FIG. 2. Reactivity of clone CS30 against a panel of anti-μ B cell blasts infected with recombinant vaccinia virus encoding the EBV latent antigens.

FIG. 3. Minimalisation experiment to define the active epitope sequence within VTAVLLHEESMQGVQVHGSM SEQ ID NO:28. This has enabled the definition of the minimal epitope as AVLLHEESM SEQ ID NO:1.

BEST METHOD OF CARRYING OUT THE INVENTION

The following examples illustrate the localisation of twelve new CTL epitopes within the EBV latent antigens using an overlapping peptide net spanning the relevant EBV antigen. The peptides were synthesised using the sequence of the B95.8 strain of EBV (Baer et al 1990). In addition, field isolates from different geographic locations were sequenced at the site of CTL epitopes YLPHEQHGM and AVLLHEESM and variants of these epitopes defined.

Abbreviations

CTL cytotoxic T-cell lymphocyte

E effector

EBV Epstein-Barr virus

HLA human leucocyte antigen

IL-2 Interleukin-2

LCL lymphoblastoid cell line

PBMC peripheral blood mononuclear cells

PHA phytohaemagglutinin

rIL-2 recombinant Interleukin-2

T target

TCM T cell medium

U/ml units per milliliter

EXAMPLE 1

Basic Culture Media for the Growth of Cells

The medium was RMPI 1640 (Commonwealth Serum Laboratories, Victoria) supplemented with 10% heat-inactivated foetal calf serum, penicillin (100IU/ml) and streptomycin (100 mg/ml). Where indicated, this medium was supplemented with purified recombinant interleukin-2 (rIL-2) (50 U/ml; Hoffman La-Roche) and 30% (v/v) heat-inactivated (56° C., 30 minutes) supernatant from the MLA 144 T-cell line. This supplemented medium was called T-cell medium (TCM) and was used in the culture of phytohaemagglutinin blast cells (PHA blasts) and for the isolation and growth of cytotoxic T-cells (CTL).

EXAMPLE 2

Preparation of Mononuclear Leucocytes and Generation of CTL

Peripheral blood mononuclear cells (PBMC) were separated (400 g or 1500 rpm, 20 minutes) from heparinized (10 U/ml) blood on Ficoll-Paque (Pharmacia, Uppsala, Sweden). The separated PBMCs were washed once in basic media and subsequently used either to stimulate CTL, PHA blasts or to establish EBV transformed cell lines.

EXAMPLE 3

HLA Typing

HLA typing of donors was performed by serology.

EXAMPLE 4

Establishment of Cell Lines

4.1 Establishment of EBV Transformed LCLs by addition of exogenous virus: EBV transformed LCLs were established from PBMCs as follows. The EBV virus stock (Table 1: specific Type and isolate), stored in liquid nitrogen is selected and rapidly thawed at 37° C. Half a milliliter of virus stock (10⁵ transformation units) is added directly into the PBMC cell pellet (1-4×10⁶ cells) and incubated for one hour at 37° C. The cells are then washed twice with media at 1000 rpm for five minutes. The cells were then made up in media with PHA (Sigma PHA-P) at 2 μg/ml and dispensed into a 24 well plate at 2×10⁶ cells/well. Clumps of cells, representing proliferating LCLs, occur within 1-3 weeks after which the cells were transferred into flasks.

4.2 Establishment of spontaneous LCLs by addition as a means of sampling field isolates of the virus: PBMCs from healthy EBV immune individuals from Australia (Brisbane), from Papua New Guinea (Goroka and Madang) or from Kenya were seeded by doubling dilution from 2×10⁶ to 1.25×10⁵ cells per 0.2 ml microtitre plate well in culture medium containing 0.1 mg/ml cyclosporin A (Sandoz Ltd., Basle, Switzerland). The cyclosporin A was maintained in the culture medium in regular refeedings for up to 8 weeks. Wells in which proliferation became apparent were subcultured and expanded at 37° C. This method was used to generate field isolates of the virus.

4.3 Establishment of PHA Blast Cell Lines: PBMC (2×10⁶ cells/24 well) were stimulated with PHA-P (2 μg/ml, final concentration) (Sigma) and after three days, TCM was added. Cultures were expanded into flasks and maintained for up to six weeks with bi-weekly replacement of TCM (without further addition of PHA).

4.4 Generation of anti-μ B cell blasts: PBMCs were separated on Ficoll-Paque (Pharmacia, Uppsala, Sweden) and depleted of T cells using E-rosetting. The enriched B lymphocytes were cultured in growth medium containing anti-IgM (μ-chain specific) coupled to acrylamide beads (Bio-Rad, California, U.S.A.), recombinant human interleukin-4 (rIL-4; 50 U/ml; Genzyme, U.S.A.) and highly purified recombinant human IL-2 from E. coli (rIL-2; 20-40 U/ml) (17,18). After 48-72 hr, B cell blasts were suspended in growth medium supplemented with rIL-2 (20-40 U/ml) (14). The B cells continue to divide 2-3 times/week for 3 weeks in the presence of rIL-2. These cells are referred to as anti-μ B cell blasts.

EXAMPLE 5

Synthesis of Peptides

5.1 Production: Peptides (purchased from Chiron Mimetopes, Melbourne) were synthesised using the pin technology in duplicate on polyethylene pins and cleaved from the pins. A C-terminal glycine ester link was used in the preparation of peptides with acid C-termini (Valerio, R. M. et al 1991).

5.2 Toxicity and Solubilization: Freeze dried peptides were dissolved first in 20 μl DMSO and then 0.6 ml distilled water to give a concentration of 2 mM. They were stored at 20° C. prior to use. Peptides were diluted in RPMI 1640 for use. Toxicity testing of all the peptides was performed prior to screening by adding peptide at a final concentration of 100 μM to 10⁴ 51 Cr labelled PHA blasts in 200 μl, in the absence of any effectors.

EXAMPLE 6

Generation of CTLs

6.1 Generation of polyclonal CTLs Polyclonal CTL effectors were generated by stimulating PBMCs from healthy seropositive donors with autologous A-type EBV transformed lymphoblastoid cell lines (LCLs) on days 0 and 7. No IL-2 was added to these cultures, as its presence favoured the expansion of non-specific T-cells (data not shown).

6.2 Agar Cloning of T-Cells. T-cell clones from individual donors were generated as follows. PBMC's were isolated and suspended in medium at a concentration of 2×10⁶ cells in 24 well plates (Costar, Cambridge, Mass.). LCL's from the same donor were irradiated at 8,000 rad and added to each of these wells at either 10⁵ or 10⁴ cells/well. After three days, cells were dispersed and seeded in 3.5 cm diameter culture dishes in 0.35 agarose (Seaplaque, FMC Corp., Rockland, Me.) containing RPMI 1640, 20% 2× RPMI 1640, 20% FCS, 16% MLA supernatant and 50 U/ml rIL-2. Colonies appear within the agar after five days. These are identified under the inverted microscope (×25 magnification) as clusters or chains or discrete cells. These colonies are harvested under the microscope in a laminar flow cabinet by suction into a Gilson pipette. Harvested colonies are dispersed into T-cell growth medium (RPMI 1640, 20% FCS, 30% MLA supernatant and 20 U/ml rIL-2) and transferred to a 96 well microtitre tray containing irradiated LCL's from the same donor (10⁴ cells/well). These colonies continue to be expanded and are stored in liquid nitrogen (approximately 5×10⁶ cells/ampoule).

EXAMPLE 7

Vaccinia virus recombinants

Recombinant vaccinia constructs for different EBV latent antigens have been previously described (Khanna et al 1992). All EBV sequences were derived from the B95.8 strain of virus. All constructs had the potential to encode the relevant full length EBV protein.

EXAMPLE 8

Chromium Release Assay

8.1 Screening CTL clones for reactivity against recombinant vaccinia encoding EBV latent antigens:

Anti-μ B cell blasts were infected with recombinant vaccinia viruses at a multiplicity of infection of 10:1 for 1 hour at 37° C. After 14-16 hours, cells were washed with basic culture medium and incubated with ⁵¹ Cr for 90 minutes, washed three times and used as targets in a standard 5 hour ⁵¹ Cr release assay as described below.

8.2 Peptide Screen: A standard five to six hour chromium release assay was performed on either polyclonal T-cell effectors or T-cell clones, to assess specificity for the peptide epitope. Briefly, washed ⁵¹ Cr (Amersham International, England) labelled (60 minutes, 37° C.) target cells (autologous PHA blasts) were added (10⁴ cells/well in 40 μl) to 10 μl of peptide (final concentration 100 μM) in a U-well 96 well plate (Nunc, Denmark). After a 30 minute incubation at 37° C., between 10⁴ and 50×10⁴ effector T-cell (cloned or bulk CTLs), in triplicate, were then added per well in 150 μl, to obtain a final effector to target ratio E:T! of 50-1:

1. Two controls were added; (i) media and target (background release) and (ii) targets (total release) for addition of 100 μl 0.5 SDS after the five hour incubation. The plate was then centrifuged at 500 rpm for five minutes and incubated at 37° C. for five hours. Following centrifugation at 1000 rpm for five minutes, 100 μl supernatants were removed for gamma counting. Results are expressed as % chromium release calculated as mean counts of experimental wells--mean counts of control (background) wells/by total available counts determined by SDS solubilisation--mean counts of control (background) wells.

EXAMPLE 9

PCR sequencing of EBC isolated from Australia, Papua New Guinea and Kenya

The polymerase chain reaction (PCR) was used to amplify specific EBV DNA sequences in the CTL epitope regions YPLHEQHGM SEQ ID NO:23 and AVLLHEESM SEQ ID NO:1. The purified DNA used in the PCR was from spontaneous LCLs from health individuals from Australia, Papua New Guinea and Kenya. Each DNA sample was subjected to two different PCR reactions. One using primers flanking the known YPLHEQHGM region;

E3YPL5 (GAC GAG ACA GCT ACC AG SEQ ID NO:32)

E3YPL3 (GAG ATA CAG GGG GCA AG SEQ ID NO:33)

and one using primers flanking the known AVLLHEESM epitope region;

E41VT5 (TTG TTG AGG ATG ACG ACG SEQ ID NO:34)

E41VT3 (CAG TAG GGT TGC CAT AAC SEQ ID NO:35)

Each PCR reaction consisted of 1× PCR buffer (Boehringer), 0.2 mM dNTPs, the purified DNA, the respective primers and 1.5 U of Taq polymerase and then subjected to denaturation at 95° C. for 5 minutes followed by 94° C. for 15 seconds, 55° C. for 30 seconds, 72° C. for 15 seconds (35 cycles) using a Perkin Elmer 9600 PCR machine. The PCR products were then purified for sequencing using QIAquick spin columns from Qiagen and sequenced in both directions using the respective primers from the PCR reactions. A PRISM™ Ready Reaction DyeDeoxy™ Terminator Cycle sequencing kit was used to set up the sequencing reaction. Reaction samples were then run on an ABI Cycle Sequencer.

EXAMPLE 10

Identification of CTL Epitopes Within EBV Latent antigens

By way of example of the epitopes described in Table I, the following methodologies were used in the definition of the CTL epitope AVLLHEESM SEQ ID NO:1. The methods used to identify other epitopes were identical. On day 10-11, polyclonal CTLs were used to screen for reactivity against overlapping peptides from EBNA2, EBNA3, EBNA4 and LMP2A on autologous PHA blasts. As seen in FIG. 1, after screening all of the peptides from EBNA4 with polyclonal CTLs from donor CS, a single peptide, referred to as peptide 52 (VTAVLLHEESMQVQVHGSM SEQ ID NO:28) showed strong reactivity in a ⁵¹ Cr-release assay.

To confirm that this sequence was an active CTL epitope, CTL clones from donor CS were established and screened for reactivity against recombinant vaccinia-infected targets (FIG. 2). As seen in this FIG., clone CS30 recognised B cell blasts infected with recombinant vaccinia encoding EBNA4.

To minimalise the epitope within this 20 mer sequence, overlapping 9 mer peptides were synthesized, and as can be seen AVLLHEESM SEQ ID NO:1 is the confirmed minimal epitope within the 20 mer peptide. The overlapping peptides from EBNA4 used to demonstrate this minimal overlapping sequence are listed on FIG. 3. A/B EBV type specificity and HLA restriction was determined using standard protocols and demonstrated that the epitope was restricted through HLA B35 and was type A specific (Khanna et al, 1992).

As already mentioned the overlapping peptides were based on the EBV sequence of the B95.8 virus. It was important to determine if field isolates of the virus from different geographical locations also included this sequence. Using PCR sequencing of the EBV sequence present in spontaneous cell lines derived from healthy individuals from Australia (Brisbane), from Papua New Guinea (Goroka and Madang) and from Kenya identified two variants. Two variants of the B95.8 sequence were defined, TVLLHEESM SEQ ID NO:19 and TALLHEESM SEQ ID NO:16 (Table 2).

EXAMPLE 11

Subunit Vaccines

11.1 Vaccine Formulation

Development of new vaccines against a variety of diseases, particularly viral infections, where CD8+ cytotoxic T-cells (CTL) play an important protective role has been hampered by the inability of conventional vaccine formulations to induce protective CTL. Although CTL are readily induced when attenuated viruses are used, in many cases attenuation is difficult, inappropriate and/or unreliable. Conventional killed virus or recombinant protein formulations do not normally gain access to the cytoplasm of antigen presenting cells (APC) and are thus not appropriately processed and presented on class I MHC. A variety of vaccination strategies have been developed to deliver antigen to the cytoplasm of APCs (ie. immunostimulatory complexes ISCOMs!, DNA, fusiogenic proteolysosomes and virus like particles). Such approaches often involve complex formulations which can be difficult to standardise, can result in unstable products and/or may only work for antigens with specific characteristics. An alternative strategy has been to use synthetic peptide CD8+ CTL epitopes as immunogens. This approach has several general advantages; peptides are stable, well defined, easy to manufacture, no infectious material is required for manufacture and the use of potentially pathogenic recombinant proteins can be avoided.

CTL epitopes-formulated with Incomplete Freunds adjuvant (IFA) usually in the presence of a CD4+ helper epitope, have been used to induce CTL in a number of animal systems. Unfortunately, IFA is extremely unlikely, due to its toxicity, to ever be licensed for use in humans. Scalzo, T. et. al. (in preparation) have examined several adjuvants currently approved, or close to approval, for use in humans to ascertain which would be able to induce protective CTL with a synthetic peptide immunogen. Protection was assessed using the Balb/c murine cytomegalovirus (MCMV) model, in which the predominant protective response has been shown to be due to CD8+ CTL directed against the epitope YPHFMPTNL SEQ ID NO:27, derived from the immediate early antigen 1 (IE-1). The presence of active CTL was confirmed using in vitro CTL assays. Scalzo, T. et. al. found that only one formulation, Montanide ISA 720/tetanus toxoid/peptide efficiently induced protective CTL.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

                  TABLE 1     ______________________________________     CTL peptide epitopes of Epstein-Barr virus within     the latent antigens of the virus                                          A/B     CTL EPITOPE   EPITOPE     HLA RE-    SPECI-     SEQUENCE      INCLUDED IN:                               STRICTION  FICITY     ______________________________________     QAKWRLQTL     EBNA3       B8         A     SEQ ID NO:11     RYSIFFDY      EBNA3       A24        A     SEQ ID NO:13     HLAAQGMAY     EBNA3       UNDEFINED  A     SEQ ID NO:5     YPLHEQHGM     EBNA3       B35.(3)    A     SEQ ID NO:23     *YPLHKQHGM     SEQ ID NO:25     *YRLHEQHGM     SEQ ID NO:26     *YPLHEQRGM     SEQ ID NO:24     SVRDRLARL     EBNAS       A2         A/B     SEQ ID NO:15     AVLLHEESM     EBNA4       B35        A     SEQ ID NO:1     #TVLLHEESM     SEQ ID NO:19     #TALLHEESM     SEQ ID NO:16     VSFIEFVGW     EBNA4       B57        A/B     SEQ ID NO:22     FRKAQIQGL     EBNA6       B57        A     SEQ ID NO:3     PYLFWLAAI     LMP2A       A23        A/B     SEQ ID NO:10     TVFYNIPPMPL   EBNA2       HLA DR/DQ  A     SEQ ID NO:18     VIETPYKPTW    EBNA4       B44        A     SEQ ID NO:22     PGDQLPGFSDGRACPV                   EBNA3       A29        A     SEQ ID NO:9     ______________________________________      *sequence variants of YPLHEQHGM SEQ ID NO:23      #sequence variants of AVLLHEESM SEQ ID NO:1

Existence and Use of Variant Sequences: The epitopes presented in table 1 are based on B95.8 sequence of Epstein-Barr virus. We have examined field isolates of the virus from Papua New Guinea, Australia and Kenya and sequenced these at the sites of two CTL epitopes. These epitopes are AVLLHEESM SEQ ID NO:1 and YPLHEQHGM SEQ ID NO:23. The results presented in Tables 1 and 2 and demonstrate that there is variation at the site of these epitopes in field isolates. At this stage, it is not known whether these variant sequences are CTL epitopes. If subsequent tests demonstrate that these represent active epitopes, then each could be included in a peptide-based vaccine.

                                      TABLE 2     __________________________________________________________________________     Variation in the HLA B35-reatricted EBNA4     Epitope AVLLHEESM in Different Ethnic Groups.     Virus     Isolate         Origin               Epitope Sequence     __________________________________________________________________________     B95.8         Caucasian               GCA                  GTT                     CTA                        CTT                           CAC                              GAA                                 GAA                                    TCC                                       ATG                                          SEQ ID NO:29     JB  Caucasian               A  V  L  L  H  E  E  S  M  SEQ ID NO:1     LC  Caucasian     DD  Caucasian     MB  Caucasian     GK  Caucasian     AF6 Kenyan     AF7 Kenyan     AF19         Kenyan     RM  Caucasian     AF1 Kenyan     LP  Caucasian     AF3 Kenyan     AF5 Kenyan     AF13         Kenyan     JD  Caucasian               ACA                  GTT                     CTA                        CTT                           CAC                              GAA                                 GAA                                    TCC                                       ATG                                          SEQ ID NO:30     RE  Caucasian               T  V  L  L  H  E  E  S  M  SEQ ID NO:19     PM  Caucasian     H25 PNG* High     H19 PNG High     H33 PNG High     L5  PNG Low     L23 PNG Low     H36 PNG High     H21 PNG High     AF16         Kenyan     H7  PNG High     L42 PNG Low               ACA                  GCT                     CTA                        CTT                           CAT                              GAA                                 GAA                                    TCC                                       ATG                                          SEQ ID NO:31     H23 PNG High               T  A  L  L  H  E  E  S  M  SEQ ID NO:16     L43 PNG Low     H26 PNG High     L8  PNG Low     H35 PNG High     __________________________________________________________________________      *Papua New Guinea

REFERENCES

Khanna, R., Burrows, S., Kurilla, M., Jacob, C. A., Misko, I., Sculley, T. B., Kieff, E., and Moss, D. J. (1992). Localisation of Epstein-Barr virus CTL epitopes in healthy immune donors using recombinant vaccinia: implications for vaccine development. J. Exp. Med., 176, 169-176.

Moss, D. J. and Suhrbier; A. Epstein-Barr virus vaccines: Prospects and limitations, 1993, Todays Life Sciences 5, 30-34.

Baer, R., A. T. Bankier, M. D. Biggin, P. L. Desinger, P. J. Farrell, T. J. Gibson, G. Halfull, G. Hudson, C. Satchwell, C. Sequin, P. Fuffnell, and B. Barrell. 1984. DNA sequence and expression of the B95-8 Epstein-Barr virus genome, Nature 310, 207-211.

    __________________________________________________________________________     SEQUENCE LISTING     (1) GENERAL INFORMATION:     (iii) NUMBER OF SEQUENCES: 36     (2) INFORMATION FOR SEQ ID NO:1:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:     AlaValLeuLeuHisGluGluSerMet     15     (2) INFORMATION FOR SEQ ID NO:2:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:     GluGluSerMetGlnGlyValGlnVal     15     (2) INFORMATION FOR SEQ ID NO:3:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:     PheArgLysAlaGlnIleGlnGlyLeu     15     (2) INFORMATION FOR SEQ ID NO:4:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:     HisGluGluSerMetGlnGlyValGln     15     (2) INFORMATION FOR SEQ ID NO:5:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:     HisLeuAlaAlaGlnGlyMetAlaTyr     15     (2) INFORMATION FOR SEQ ID NO:6:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:     LeuHisGluGluSerMetGlnGlyVal     15     (2) INFORMATION FOR SEQ ID NO:7:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:     LeuLeuHisGluGluSerMetGlnGly     15     (2) INFORMATION FOR SEQ ID NO:8:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:     MetGlnGlyValGlnValHisGlySer     15     (2) INFORMATION FOR SEQ ID NO:9:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 16 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:     ProGlyAspGlnLeuProGlyPheSerAspGlyArgAlaCysProVal     151015     (2) INFORMATION FOR SEQ ID NO:10:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:     ProTyrLeuPheTrpLeuAlaAlaIle     15     (2) INFORMATION FOR SEQ ID NO:11:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:     GlnAlaLysTrpArgLeuGlnThrLeu     15     (2) INFORMATION FOR SEQ ID NO:12:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:     GlnGlyValGlnValHisGlySerMet     15     (2) INFORMATION FOR SEQ ID NO:13:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 8 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:     ArgTyrSerIlePhePheAspTyr     15     (2) INFORMATION FOR SEQ ID NO:14:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:     SerMetGlnGlyValGlnValHisGly     15     (2) INFORMATION FOR SEQ ID NO:15:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:     SerValArgAspArgLeuAlaArgLeu     15     (2) INFORMATION FOR SEQ ID NO:16:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:     ThrAlaLeuLeuHisGluGluSerMet     15     (2) INFORMATION FOR SEQ ID NO:17:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:     ThrAlaValLeuLeuHisGluGluSer     15     (2) INFORMATION FOR SEQ ID NO:18:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 11 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:     ThrValPheTyrAsnIleProProMetProLeu     1510     (2) INFORMATION FOR SEQ ID NO:19:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19:     ThrValLeuLeuHisGluGluSerMet     15     (2) INFORMATION FOR SEQ ID NO:20:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 10 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:20:     ValGluIleThrProTyrLysProThrTrp     1510     (2) INFORMATION FOR SEQ ID NO:21:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:21:     ValLeuLeuHisGluGluSerMetGln     15     (2) INFORMATION FOR SEQ ID NO:22:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:22:     ValSerPheIleGluPheValGlyTrp     15     (2) INFORMATION FOR SEQ ID NO:23:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:23:     TyrProLeuHisGluGlnHisGlyMet     15     (2) INFORMATION FOR SEQ ID NO:24:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:24:     TyrProLeuHisGluGlnArgGlyMet     15     (2) INFORMATION FOR SEQ ID NO:25:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:25:     TyrProLeuHisLysGlnHisGlyMet     15     (2) INFORMATION FOR SEQ ID NO:26:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:26:     TyrArgLeuHisGluGlnHisGlyMet     15     (2) INFORMATION FOR SEQ ID NO:27:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:27:     TyrProHisPheMetProThrAsnLeu     15     (2) INFORMATION FOR SEQ ID NO:28:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 19 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:28:     ValThrAlaValLeuLeuHisGluGluSerMetGlnValGlnValHis     151015     GlySerMet     (2) INFORMATION FOR SEQ ID NO:29:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 27 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:29:     GCAGTTCTACTTCACGAAGAATCCATG27     (2) INFORMATION FOR SEQ ID NO:30:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 27 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:30:     ACAGTTCTACTTCACGAAGAATCCATG27     (2) INFORMATION FOR SEQ ID NO:31:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 27 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:31:     ACAGCTCTACTTCATGAAGAATCCATG27     (2) INFORMATION FOR SEQ ID NO:32:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 17 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:32:     GACGAGACAGCTACCAG17     (2) INFORMATION FOR SEQ ID NO:33:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 17 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:33:     GAGATACAGGGGGCAAG17     (2) INFORMATION FOR SEQ ID NO:34:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 18 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:34:     TTGTTGAGGATGACGACG18     (2) INFORMATION FOR SEQ ID NO:35:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 18 base pairs     (B) TYPE: nucleic acid     (C) STRANDEDNESS: single     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:35:     CAGTAGGGTTGCCATAAC18     (2) INFORMATION FOR SEQ ID NO:36:     (i) SEQUENCE CHARACTERISTICS:     (A) LENGTH: 9 amino acids     (B) TYPE: amino acid     (C) STRANDEDNESS:     (D) TOPOLOGY: linear     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:36:     TyrLeuProHisGluGlnHisGlyMet     15     __________________________________________________________________________ 

We claim:
 1. A cytotoxic Epstein-barr virus T-cell epitope, the epitope being selected from the group consisting of QAKWRLQTL (SEQ ID NO:11), RYSIFFDY (SEQ ID NO:13), HLAAQGMAY (SEQ ID NO:5), YPLHEQHGM (SEQ ID NO:23 , YPLHKQHGM (SEQ ID NO:25), YRLHEQHGM (SEQ ID NO:26), YPLHEQRGM (SEQ ID NO:24), SVRDRLARL (SEQ ID NO: 15), AVLLHEESM (SEQ ID NO: 1), TVLLHEESM (SEQ ID NO: 19), TALLHEESM (SEQ ID NO: 16), VSFIEFVGW (SEQ ID NO: 22), FRKAQIQGL (SEQ ID NO: 3), PYLFWLAAI (SEQ ID NO: 10), TVFYNIPPMPL (SEQ ID NO: 18), PGDQLPGFSDGRACPV (SEQ ID NO: 9) and VEITPYKPTW (SEQ ID NO: 20).
 2. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is QAKWRLQTL (SEQ ID NO:11).
 3. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is RYSIFFDY (SEQ ID NO: 13).
 4. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is HLAAQGMAY (SEQ ID NO:5).
 5. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is YPLHEQHGM (SEQ ID NO:23).
 6. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is SVRDRLARL (SEQ ID NO: 15).
 7. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is AVLLHEESM (SEQ ID NO: 1).
 8. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is VSFIEFVGW (SEQ ID NO: 22).
 9. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is FRKAQIQGL (SEQ ID NO: 3).
 10. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is PYLFWLAAI (SEQ ID NO: 10).
 11. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is TVFYNIPPMPL (SEQ ID NO: 18).
 12. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is PGDQLPGFSDGRACPV (SEQ ID NO: 9).
 13. A cytotoxic Epstein-barr virus T-cell epitope, as claimed in claim 1 in which the epitope is VEITPYKPTW (SEO ID NO: 20).
 14. A cytotoxic Epstein-Barr virus T-cell epitope, as claimed in claim 1 in which the epitope is a variant of YPLHEQHGM (SEQ ID NO:23) the variant being selected from the group consisting of YPLHKQHGM (SEQ ID NO:25), YRLHEQHGM (SEQ ID NO:26) and YPLHEQRGM (SEQ ID NO:24).
 15. A cytotoxic Epstein-Barr virus T-cell epitope, as claimed in claim 1 in which the epitope is a variant of AVLLHEESM (SEQ ID NO: 1), the variant being selected from the group consisting of TVLLHEESM (SEQ ID NO: 19) and TALLHEESM (SEQ ID NO: 16).
 16. A method of preparing a composition, method comprising admixing at least one cytotoxic Epstein-Barr virus T-cell epitope as claimed in any one of claims 1-15 with at least one pharmaceutically acceptable adjuvant, carrier, diluent or excipient. 